Christopher Cheung Wah-fung, the chairman of Christfund Securities, the biggest mainland brokerage in Hong Kong, expects the on-again, off-again plan to allow mainland investors to invest directly in Hong Kong stocks to materialise this summer. Mr Cheung, a delegate to the National Committee of the Chinese People's Political Consultative Conference, said yesterday that implementation details of the 'through-train' scheme would be finalised following the central government's political consultative and National People's Congress sessions. 'The [Hong Kong] stock market has slumped sharply recently, partly because rumours spread that the through-train plan had been derailed,' he said. 'But I don't think so. The scheme is still in the making and all the authorities concerned are working out details seriously.'